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osteodoc08
04-20-2014, 06:28 PM
I have a 4 cavity MP Brass mold of the H&G 258 clone. It seems that I am either struggling to get the boolit to release and they are purty or I spew up my tempo and they rain out of it with a tap but are frosty to the point of grainy appearance. It wipes off easily, can still be sized to .411 but are 1-2grains less than the purty ones.

I've tried increasing the melt temp from 675-750, allowing the mold to cool a bit, cleaning the mold completely (after allowing to fully cool). I just can't seem to find the sweet spot. I struggled through about 20# of melt and have a box of completely usable boolits, but just looking for some nugget of wisdom on this. This has the been the most aggravating mold ever.

JSnover
04-20-2014, 07:24 PM
Try breaking the edge of the cavity: scrape lightly and carefully with a razor blade or jewelers file, just enough to deburr/relieve the edge. Fine sand paper might also work, the important thing is only work on the edge, not the face of the block or inside of the cavity.

Sweetpea
04-21-2014, 12:12 AM
Is this a NEW mould?

Brass can be the most frustrating thing when new, needs to "age" and "patina".

longbow
04-21-2014, 12:27 AM
You have to keep the mould temperature up by casting at steady and relatively fast cadence. Don't stop to admire or examine the boolits while casting unless they have obvious defects like wrinkles.

I wouldn't worry about frosting at all, it hurts nothing. If the boolits are slightly frosted but well filled out there is nothing wrong with them.

Being a Mihec mould, I would not take JSnover's advice just yet. Deburring can certainly solve sticking boolits but to be honest, I would be very surprised if you have Mihec mould with burrs on it. Before randomly trying to deburr, take a look with a magnifying glass to see if there are burrs first (and it is possible there are). Another trick is to drag a cotton swab around the edges of the cavities ~ if fibers pull off then there may be burrs but check to be sure it isn't vent line edges catching fibers.

A bit of tin may help fillout as well but generally, I find that if I run fast and hot my Mihec moulds cast perfect boolits. Also, I cut the sprue as soon as it solidifies but is still slightly soft then invert the mould and give the Cramer sliders a push. If everything is up to temperature the boolits move out with the pins and drop off.

If this is a solid version (no Cramer pins) then no pin issues but keeping that mould up to temperature is still an issue so again, cast fast and keep that mould hot.

I pre-heat the mould until the sprue plate lube just starts to smoke. A good pre-heat can solve many casting problems and makes it easier to get going and keep that mould up to temperature. It also makes it obvious if the mould temperature starts dropping because then they may start to stick or slight frosting disappears, etc.

Boolits do not need to be shiny to work, they need to be well filled out and consistent in size and weight.

My Mihec moulds are my favourites.

Longbow

osteodoc08
04-21-2014, 09:06 AM
You have to keep the mould temperature up by casting at steady and relatively fast cadence. Don't stop to admire or examine the boolits while casting unless they have obvious defects like wrinkles.

I wouldn't worry about frosting at all, it hurts nothing. If the boolits are slightly frosted but well filled out there is nothing wrong with them.

I find that if I run fast and hot my Mihec moulds cast perfect boolits. Also, I cut the sprue as soon as it solidifies but is still slightly soft then invert the mould and give the Cramer sliders a push. If everything is up to temperature the boolits move out with the pins and drop off.

I pre-heat the mould until the sprue plate lube just starts to smoke. A good pre-heat can solve many casting problems and makes it easier to get going and keep that mould up to temperature. It also makes it obvious if the mould temperature starts dropping because then they may start to stick or slight frosting disappears, etc.

Boolits do not need to be shiny to work, they need to be well filled out and consistent in size and weight.

My Mihec moulds are my favourites.

Longbow

This is what I'm finding. I cut the sprue by hand when everything is up and running as it should and when I get the temp of the melt at 725-750 and have a fast cadence with the mold, they rain bullets. I open and they fall. No beating, no frustration, just a little more frosted boolits than what I'm used to. They have a grainy appeance when cooled and are satin if wiped. Just more frosting than I am accustomed to and like to see. They are well filled out and completely useable. I typically cast at 650-675 and have nicely filled out shiny purty boolits. I guess I'm just being a boolit snob (J/K of course)

gray wolf
04-21-2014, 09:48 AM
Your not being a bullet snob, I have the same problem with a brass mold. What normally works for me does not work with brass. If I set up and work like I would with an iron mold it makes me want to quit out of frustration.

If I cast at my normal 675* the bullets drop but are not filled out, if I bump the temp a little they fill out but refuse to drop out. I have to cast hot enough and fast enough so that I can cut the sprue with my thumb.

Then I fight with having to keep applying oil to the sprue plate or the molten lead sticks on it after a few cast.

Read ON:

Now that's what I would have said before I took the advise of the folks here that are smarter than me. I took a long hard look at the edges of my mold cavities and found they were slightly rolled in ( only way I know how to say it ) they were locking the bullets into the cavities.

I took a very sharp blade and ran it on the outside edge of each cavity, not the inside and not the mold face.
Running my pot at 725* and casting with a rather brisk cadence my problems
went away. Now a slight tap on the mold hinge or a hard shake of the mold and the bullets fall out for me. I do have to cut the sprue a little early and I over came that by just using the mold lube a more often than with different molds.

I find brass is a different Animal and sometimes you need to be an animal trainer of sorts Eh.

JSnover
04-21-2014, 08:20 PM
I took a long hard look at the edges of my mold cavities and found they were slightly rolled in ( only way I know how to say it ) they were locking the bullets into the cavities.

I took a very sharp blade and ran it on the outside edge of each cavity, [COLOR="#FF0000"]not the inside and not the mold face.[/QUOTE]

I've found the same thing and cured it the same way. Breaking a sharp edge is not a big deal and will not ruin a mold.

Le Loup Solitaire
04-21-2014, 09:07 PM
A trick/gimmick used by some mold owners/casters to help find burrs on cavity edges is to roll and smooth a q-tip or don't do it, but to pass the q-tip along the cavity edges and the burr if there is one will catch some of the q-tip fibers and show where it is. it takes a good eyeball or some help with with a magnifying glass/loupe. Previous two posts have good instruction for using a sharp edge to get rid of the burrs, but go slowly and carefully. LLS